1. Field of the Invention
An aspect of the invention relates to a data storage device.
2. Description of the Related Art
The recoding densities of storage media, such as magnetic disks, magneto-optical disks, and optical disks, are dramatically improving. Consequently, storage devices can be miniaturized and the storage capacities thereof can be increased, which leads to improved convenience of the storage devices.
For such high-density storage media, in order to precisely position a head over a target track, a servo track writer (STW) is used to write servo information, such as a track numbers and a servo pattern (or servo marks) for demodulation of the head position relative to the center of the track. The STW writes the servo information from the outer side or inner side of the storage medium. A control device, such as a storage device, uses the servo information to perform automatic control of the head for writing/reading data to/from the storage medium (refer to Japanese Patent No. 2645182).
The servo information writing using the STW has problems in that erasing called “side fringing” causes deterioration in the quality of servo information written to the storage medium, when the head reads the servo information, for example, servo-mark reading error and gray-code false detection occur.